Levels of norepinephrine and dopamine were measured in eight discrete regions of the hypothalamus in three groups of male rats: genetically obese, non-obese and castrated non-obese. DA levels showed no significant differences among the groups in any of the regions. NE levels in the paraventricular nucleus were significantly lower in the obese and castrated animals than in the normal animals. In the median eminenece, NE levels were significantly decreased for the castrated group. None of the other regions sampled showed significant differences in NE levels.